Valve for pressure cookers



May 14, 1940. l P. w. STEPHNS 2.200.903

, VALVE FOR PRESSURE COOKERS zZ/ewfw@ May 14 1940- P. w. sTEPHEN 2,200,903

VALVE FOR PRESSURE COOKERS Filed Feb. 4, 19s? 2 sheets-sheet 2 Patented May 14, 1940 UNITED STATES PATENT oi-Fl'cs This invention relates to pressure cookers, and more particularly to improved safety valves therefor.

The present application is a continuation in i part of application No. 89,189, filed July 6, 1936,

for a Pressure cooker.

One feature of this invention is that it provides a safety valve for a pressure cooker; another feature of this invention is that the valve is so constructed and arranged as not to blow on operative position on the cooker upon escape of 4vapor therefrom; a further feature of this invention is that a chamber is provided adjacent t-he valve member for expansion of the released vapor; another feature is that the chamber communicates with atmosphere throughout a relatively large area, so that vapor may be readily vented from the chamber .to atmosphere; yet another feature is that a pressure gauge may be incorporated with the safety valve; other features and advantages of this invention will be apparent from the following specification and the drawings, invwhich':

Figure l is a fragmentary sectional view of a pressure cooker having thereon a valve embodying this invention; Fig. 2 is a detailed sectional view of the valve arrangement shown in Fig. 1; Fig. 3 is a top plan view ofthe valve shown in Fig. 2; Fig. 4 is a vertical sectional view of a 30 modified form; Fig. 5 is a top plan view of the valve shown in Fig. 4; Fig. 6 is a top plan view of another modification; Fig. 'l is a vertical sectional view along the line 1-1 of Fig. 6; Fig. 8 is a vertical sectional view along the line 8 0 of Fig. 6; Fig. 9 is a top plan view of a safety valve incorporating a pressure gauge; Fig. 10 is a side elevation of the valve shown in Fig. 9; Fig. 11 is a vertical sectional view along the line Ii-Ii of Fig. 9; Fig. 12 is a top view along the line |2 I2 of Fig. 11; Fig. 13 is a vertical sectional view showing a lifting knob; and Fig. 14 is a horizontal sectional view along the line H-Il of Fig.' 13. l

In order to protect against excessive pressures within a pressure cooker ancl to make-it' safe for normal household use, it is necessary to` provide a relief vaive'lin some part thereof, (usually the cover. When pressure in the cooker rises above the desired maximum. this valve should vent the pressure without losing its operative relation with the cooker, so that when the pressure is reduced to a safe point, the valve 'will again close the opening and seal the cooker. Trouble has heretofore beenexperienced upon venting the pres- J sures in that the valve `has blown completely off the cooker or to such ya position that it would not return to closed or sealing position when the pressure had dropped within safe limits.

I'he present invention provides a safety valve having a member adapted to close an opening communicating with the cover of the cooker. 'I'he valve body about the valve member has therein a relatively large chamber which communicates with atmosphere through a number of openings providing a relatively large area. lo

`This enables vapor within the cooker to expand in the chamber and vent to atmosphere without exerting suilicient upward pressure on the valve body to blow it off the cooker.A

As discussed in the application of which this 15 is a continuation, it is preferable to arrange interlocking means between the closure means sealing the cover to the cooker and the valve, so that the closure or cover can only be removed after the valve'has been, lifted to vent the pres- 20 sure within the cooker to atmosphere. This prevents opening the sealing means and permitting the pressure to escape around the edges of the cover, with frequent danger of burns to the housewife. The present valve is particularly adapted to interlock with sealing or closure means operated through a toggle by a lever and so constructed and arranged that the lever is immediately adjacent and locked into'the valve when the cover is sealed to the cooker.

In the particular embodiment of this invention illustrated herewith a cooker is provided with a cover 2| adapted to be sealed on the upper end of the cooker body 20 by the wedging action of a exible sealing ring 22. This sealing ring is drawn into sealing engagement by a manually operable lever having a portion 23 adapted to interlock withthe valve and prevent removing of the seal until the valve has been lifted and the pressure within the cooker vented to atmosphere.

In the va1ve iuustrated 1n Figs. 1 to 3, which 40 valve was also fully shown and described in my application No. 89,189, a valve 24 has a valve body 25 which is shown as of cast metal. The valve body has a relatively large chamber 26 in the upper part thereof, with openings 2l through 45 the top thereof giving communication between the chamber 26 and atmosphere. A cone shaped valve member 28 projects downwardly into the chamber 26 fromthe top of the valve body 25, and is adapted to close the opening at the top of the tube 29, which tube is threaded into an opening 30 in the cover 2i, and thus communicates with the interior of the cooker. The valve body 25 is provided with handles 3l of heat insulating mate- 55v rial enabling it to be conveniently removed when the cooker is hot. 'I'he internal diameter of the tube 29 and the weight of thevalve 24 are so proportioned that pressures up to the desired maximum will not liftthe valve member 23 from its sealing position inthe top of the tube 29; as soon as the pressure within the cooker exceeds the desired maximum, however, the upward force exerted Von the valve member 23 is sumcient to lift it from its seat in. the topy of the tube 2s, thus venting the vapor pressure within the cooker into f the chamber 26. Since-this chamber is relatively large with respect to the sizeof the passage -through the tube ze and Yhas. di' plurality of relatively large'openings 21 in the top thereof communicating to atmosphere, the vapors coming lup through the tube are able to expand in the chamber 23 and pass to atmosphere without their expansion reaction throwing the valve body up high enough to disturb the operative relationship between the conical valve member 28 and the tube 29. 'Ihus after the pressure has vented itself to a safe point the valve 2,3 again drops into position, Vclosing the tube 29. In-asmuch as -a relatively pand sideways without exerting all of their force upwardly on the valve member; similarly, the

large area oi communication with atmosphereMA enables them to pass from. the chamber to atmosphere without creating a back pressure which would tenci to prevent ready passage of vapors from the tube into theexpansion chamber. In the particular embodiment of this invention disclosed herewith thel internal diameter of the tube isand the valve weight eight ounces, the

' relief valve venting at a'pressure of about fifteen Vportion forms the valve member adapted to close the tube 35. The spaces 38 between the arms 33 provide openings of relatively large area permitting communication between the chamber 31=and atmosphere. 'I'he side walls of the valve have a shoulder 39 bumped or stamped therein and adapted to form an upper stop against which a' heavy annular washer or guide 39 of metal may abut. 'Ihis metal serves as a weight to regulate the total weight of the valve, and is provided with an opening 4,9 therein disposed beneath the conical member 34v and adapted' to receive a tube 35. At the bottom edge of the valve body the metal is turned inwardly and'upwardly, as at 4I, against the bottom of the metal weight 39 to hold it in position within the valve. This portion 4I also serves as an abutment against which the portion 42 of the sealing lever may be lockedl to prevent removal of the seal prior to venting ot the'pressure within the cooker.

In the modified form of this invention illustrated in Figs. 6 to 8f a construction is shown whereinV the valve halsba body portion 43 with' a bridge member 44 lifted thereabove, and an opening 45 therein adapted to receive. the tubevextending out of the cover of the pressure cooker. A larger opening at the bottom of the valve prolarge chamber is provided about the opening at the top of the tube, the vapors are'enabled to ex-v vides a shoulder 4I against whichrthe actuating means of the sealing device for the cover may be locked. 'I'he bridge carries a conical valve member 4l registering with the opening 45 and adapted to close the top of the tube'withwhich the valve is used. In this modification the expension chamber constitutes that portion about the tube beneath the bridge 44, and openings'on each side of the bridge to atmosphere freely permit vapors to escape horizontally from the top of the tube through the partially enclosed chamber to atmosphere.-

In addition to a safety valve, it is preferable to have a pressure gauge reading the pressure within the cooker'in poundsl per square'l inch, ior ex-l ampleyand most pressure cookers are vso provided.

This is normally attached to the cover or to the body of the cookeras a separate and distinct unit from the safety valve. In the modification illustrated in Figs. 9 to `12, however,.the pressure gauge and safety valve are incorporated in a single unit. The valve 48 is here shown as comprising a body portion 49 of heat insulating material,

such as molded, resin or phenolic condensation product. This body is provided with a plurality, vhere shown as four, of upwardly extending arms 50 forming va socket 5i therewithin adapted to receive a pressure gauge of common commercial type having an outer housing or casing 52 of substantially cylindrical shape. Thev gauge is heldin the body portion 49 by any convenient means, here s hown as two bolts 53 extending through openings in the/clasing 52.

,The body portion 49 has vertically, through the `center thereof, an opening 54 adapted to surround the tube 55 Yextending up from the coverA 56 of the cooker. This tube is shown as being locked to the cover between a shoulder 51 and a.

swedgedportion 58.' 'Ihe tube 55 is hereshown as surrounded with a tube 59 of heat insulating material similar to the body of thevalve, which tube-59 is rigidly and permanently fastened to the tube 55 and is adapted to have the opening 54 in the body 49 slide readily thereover.

The casing of the pressure gauge 60 has at the bottom thereof a conical member 6I adapted to act as a valve member to close the top of the tube 55. This conical member 9| has therethrough at the axis thereof an opening 92, through which opening pressure 'withinA the cooker is admitted to the gauge -to actuate pointer 53 on the scale 64 provided therefor. Inasinuch as this opening coincides with the apex of the conical member 6I it is always in communication with the pressure within the cooker, even whenthe body and threaded into combination with the internal diameter of -the be read from the scale 94 vof the range, thus enabling the housewife to turn down the fire somewhat if the pressure rises too much, in order to u' prevent an undesired loss of vapors through the safety valve. v

'I'he tube 59 of heat insulating material about the metal tube 5i enables the cover to be readily picked up thereby after the valve has been removed fromthe tube. 'I'his tube is here shown as having a pair of projecting wings 61 lying in slots in the valve body 49 when the valve is in place thereover. Referring more particularly to Figs. 13 and 14, it will be seen that these wings 61 provide means for locking a knob 68 in place over the tube when the valve has been removed. 'Ihe knob 68 is merely dropped over the tube with the wings 61 coinciding with slots 69 in the knob, and then given a partial turn to lock it in place. 'Ihis knob, although not neccessary, may be used where it is desired to obviate any possibility of the hand being burned by contact with the metal tube 55 or by any residual vapor passing up through said tube, Where the cooker is being used as an ordinary kettle, and not'under pressure, the valve and sealing means may be left of! and the knob left in place over the tube during such usage.

While I have shown` and described certain embodiments of my invention, it is to be 'understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is my invention to claim all novelty inherent inmy invention as broadly as permissible, in view of the prior art.

I claim:

1. A safety valve for a pressure cooker having a vertical tube opening thereinl including: a valve member adapted to close the end of said tube and be supported thereby; a valve body of heat insulating material carried by said member and having upwardly projecting portions forming a socket; a pressure gauge adapted to be received by said socket and fastened therein, said gauge and body cooperating to form a chamber of relatively large dimensions surrounding said valve member and communicating to atmosphere through a relatively large area between said upwardly projecting po tions; and means whereby said gauge communicates with said tube, said means comprising an opening through said valve member.

2. Apparatus of the character claimed in claim 1, wherein said tube is surrounded by a tube of heat insulating material fastened thereto.

PERCY W. STEPHENS. 

